Monday, April 27, 2015

A Pair of Amazing Supercells: April 26, 2014 Comanche, Erath and Eastland Counties

Way back when, in the late 1990s, I was a pretty dedicated storm chaser. The title of this blog, in fact, had its genesis from a website I maintained consisting primarily of storm chase reports. But time marched on--marriage, family, other responsibilities, and the idea of hopping in a car and driving 700 miles over a weekend chasing storms passed by the wayside.

The past year or so, the idea of getting out and seeing the atmosphere in turmoil has gotten more appealing, and much easier (though many will disagree with me) with wireless technology we couldn't have dreamed of in 1996. The downside of this, of course, is that even the casual storm chaser has more information at their fingertips than ever before, which results in traffic jams, unsafe driving situations, and the increased chances that someone who doesn't know what they're doing will get into trouble poking at the bear.

I'll make the disclaimer here that I don't purport to be a meteorologist, nor a storm researcher. I once studied the atmosphere intently before chasing, did hand charts, looked at upper air charts and models. I don't do that anymore. I'm content with driving to see a beautiful storm, flanking it to reposition for more photographs, and to enjoy the "Wonder of Nature." And be safe, stay out of the way of the nasty parts, and try to be aware of a storm's evolution.

All this is a long introduction to this report of Sunday's storm chase. It had been an active week for severe weather in North Texas, but obligations have prevented me from chasing. I was due back at work Sunday evening, but forecasters proved an early afternoon event not far west of DFW, so I was more than game to head out, accompanied by Travis Berryman and Jim Hollis.

That morning, the Storm Prediction Center gave the area between the Red River, Interstate 35 and the Hill Country an "Enhanced" risk for severe weather, mostly heavy rain, high winds and large hail, with a better chance for "a few strong tornados" south of I-20. Before we headed out, SPC had upgraded the risk to "Moderate," the first time I'd seen such a designation this spring.

I'll admit we were traveling a little light for technology. A tattered copy of The Roads of Texas--very old school. A car radio, but no knowledge of what the best AM/FM stations to listen to would be. And a trio of smart phones. I was running both the Radar Scope and Storm Spotter apps--when the connection is there, it is truly amazing to have such information right there, all the time. The was unheard of years ago at the turn of the century, where the MOST advanced chasers had perhaps satellite internet; otherwise, you grabbed data when and where you could: truck stops, hotel lobbies, maybe a public library. Going out into this, I'd recommend carrying a good scanning radio to listen to SKYWARN spotters. We didn't even have that--need to put it on the list for the next chase.

By 1230, small rain showers had popped up around 50 miles West of Fort Worth, but the real action would be a little west of Abilene, where already robust storms had fired up off the Dryline. This is where we needed to be. Before 1400, a handful of large cells had arrayed north-to-south from roughly Paducah to just near Ballinger, south of Abilene. We were westbound on I-20, which would give us quick access westward and lots of access north or south to intercept these storms, which at the time were moving north-east at around 30mph.

Nearing Ranger, a storm north and west of Abilene was growing more intense, and at 1350, the National Weather service issued a tornado warning on the storm due to radar indicated rotation. Far out! We could leave the freeway and head northwest and intercept it easily. The there was the storm to the south of the interstate that was just as intriguing, though not yet warned tornadic. Which to chase? This storm would be easier to intercept, and was moving right for us, and being south of I-20, would be in more unstable air more conducive to rotating updrafts--a good thing. We stopped for refreshments at Eastland, and by the time we returned to the car, at 1432, it had been upgraded from a Severe Thunderstorm to a Tornado Warning.

Radar of our two possible targets at 1344 as we neared Ranger, TX, just off to the radar to the right. Both storms are showing a yellow outline--severe thunderstorm warning. The would soon be upgraded to Tornado Warnings.

Now we're approaching our storm (our location is the blue circle with cross-hatches), southbound at Carbon at 1444. The storm has a pronounced hook. We 're headed to Rising Star to intercept. Note the trajectory of the storm: no longer going northeast, but taking a "right turn". Right-turning supercells are more efficient tornado producers.

We headed southwest towards Rising Star, about a dozen miles or so, and with each turn in the highway and glimpse at the storm through the mesquite trees, our anticipating grew. We had a great view of the structure of the storm: above and behind up, the big anvil top shooting east; the stout updraft tower; and to the north, a "beaver tail," a long thin cloud showing the conveyor belt of inflow air this storm was ingesting to grow larger. This is my favorite part of the chase: approaching a new storm, dark to the west, getting closer to the point you can see under the rain free updraft base, which will serve as the "hot spot" for any tornado development. And for a little bit, we're the only ones we see on the storm. The usual contingent of chasers is either closer to Rising Star or haven't yet jumped onto this storm.

A half-dozen miles northeast of Rising Star, 1503. Base of the storm is still 10 miles away. Clearly visible is the wall could under the rain-free base and the explosive updraft tower. All is still. The only sound is the rumble of thunder. The rain and hail are to our north (right of photo).

Looking to the east from the same location. you can see the eastward-racing anvil overhead, essentially the exhaust pipe from this heat-transfer machine we're chasing.

A few miles further down the road south and east at 1507. Rising Star is near that mesa in the distance.

Panorama of the whole scene at 1519. Visible to the right is the "beaver tail," a spotting feature of a robust Supercell thunderstorm.

At this point, 1527, we're in an ideal position: just east of the hook. South of the rain and heavy hail core, with a great view into the notch and hook to the left. We're feeling a lot of warm air flowing INTO the storm, feeding it further. Now the storm is headed straight east and gathering steam. . . .we can't stay here long before this is no longer a safe place to be. We head south and east to maintain our position.

Eleven minutes later, 1536, and to our left we can see sheets of rain rapidly moving from our right to the left. The wind is now blowing in our faces, probably 30-40 miles per hour. And under the wall cloud, we begin to se the beginnings of a tornado, with dust on the ground swirling upward. We've got a tornado! Though within another minute, we'll be in that rain and our view of the tornado will be gone. This will be confirmed by the NSW Fort Worth as an EF-0 intensity storm, short lived, less than a couple miles in length, maybe 50 yards wide and around 70mph speed.

Now look at the storm: it's exhibiting what's called a "Screaming Eagle" signature, with the talons (hook) and spread wings (heavy rain core spreading east. We're driving south east towards Comanche, trying to stay out of its way. The storm is heading towards DeLeon and then Dublin. Road options are limited. With luck we can get to Dublin ahead of it. . .

Seen north of us near Comanche at 1551, the tornado on the ground is obscured by sheets of rain wrapping counter-clockwise around the mesocyclone. You can see the green of the hail above the updraft.

At 1603, we're a bit north of Comanche taking the view above. Now the storm continues to turn right. The folks in De Leon are getting buried in hail; Dublin is next on the target. We briefly consider punching north into Dublin to go east towards Hico. . .

. . . but coming north out of Comanche, it's clear that we won't make it. We drive into the rain a couple miles beyond this view, but it's counter-clockwise, a heavy deluge, and easily 50mph winds. This is is the beginning of a "core punch," and we don't want an encounter with either large hail or a tornado. Several chasers had windows broken out and sheet metal damage. We didn't want that. We turn around and angle south-east towards Highway 36 and a route to Hico ahead of the storm.

This is as close as we got to the "nasty stuff." As can be seen from our Blue Circle location, we're right on the edge of the tornado circulation. . .

And as can be seen from this Storm Velocity radar scan, we're RIGHT on the edge of the mesocyclone (the close proximity of green and red colors indicates intense inbound and outbound winds) This was the storm's peak of intensity. Hail was as big as tennis balls, and the town of Dublin was buried in a couple of inches of smaller hail.

After regaining Hwy 36, we pulled the second-worse chaser boo-boo: didn't keep track of where we were going, and got away from the storm. We'd meant to cut across to another highway into Glen Rose, but missed the turn and ended up in Hamilton. By then, the storm was nearly 20 miles north of us and we were hopelessly out of position. But we were able to get this nice view of the "knuckles" hanging under the storm's anvil at 1703.

By this point, the storm was weakening. By the time we got into Glen Rose, it had collapsed and was hardly recognizable anymore. There were other storms to the west, and I had the feeling that the storm behind this one--traveling along its same enhanced instability boundary--was stealing energy from this storm. Since I had to work in a few hours, we decided to head towards Grandbury for dinner before heading home. A few miles north of Glen Rose, however, a tornado warning was issued for the storm to the west. Should we? It wasn't dark yet, and I didn't have to be home THAT early. . .we turned around to Glen Rose and headed west towards the storm leaving Stephenville, got a view of it: A HONKER STACKED-PLATE MOTHERSHIP MONSTER! We found a rise a half-dozen miles west of Glen Rose and watched it approach at 1900. It was mesmerizing.

Hey, cows--behind you!

Of all the supercells, an approaching High Precipitation storm can be among the most beautiful. Sculptured clouds like a wedding cake. A beautiful view under the updraft tower. The menacing shelf cloud ahead of the rain, behind which likes the Dark Heart of Nature: possibly a tornado, but certainly torrential rain, big hail and high winds. We watched it approach a cattle pen. The cows didn't seem that concerned.

After 20 minutes or so, the storm was moving on east. I had an idea for a photo, at the fiberglass dinosaur park along the river. Good idea, but a few minutes too late. This storm was gusting out as well and losing its steam. . . .time for home!

Behind this storm, spaced about an hour apart just like the one in front of it, was a THIRD big supercell following the same track. Each storm successively tapped better and better air before falling apart. . .this one, however, was the last in the parade, and lived the longest, eventually moving into Johnson County and laying down a mile-wide stovepipe tornado. Thankfully--no injuries or deaths, which really is the headline from this day of photogenic sparkles across the corridor south of I30. We love big storms, and especially when they don't injure or kill.